See also Raisins, Wine.
Energy value (calories per serving): Moderate
Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: Low
Major vitamin contribution: Vitamin A, vitamin C
Major mineral contribution: Phosphorus
About the Nutrients in This Food
Grapes are high in natural sugars, but even with the skin on they have less than one gram dietary fiber per serving. The most important nutrient in grapes is vitamin C. A serving of 10 green or red Thompson seedless grapes has 5.3 mg vitamin C (7 percent of the R DA for a woman, 6 percent of the R DA for a man).
The tart, almost sour flavor of unripened grapes comes from natu- rally occurring malic acid. As grapes ripen, their malic acid content declines while their sugar content rises. R ipe eating grapes are always sweet, but they have no stored starches to convert to sugars so they won’t get sweeter after they are picked.
The Most Nutritious Way to Serve This Food
Fresh and ripe.
Buying This Food
Look for: Plump, well-colored grapes that are firmly attached to green stems that bend easily and snap back when you let them go. Green grapes should have a slightly yellow tint or a pink blush; red grapes should be deep, dark red or purple.
Avoid: Mushy grapes, grapes with wrinkled skin, and grapes that feel sticky. They are all past their prime. So are grapes whose stems are dry and brittle.
Characteristics of Different Varieties of Grapes
Cardinal Large, dark red, available March–August Emperor Large red with seeds. September–March Flame Seedless, medium to large, red. June–August R ibier Large, blue-black, with seeds. July–February Tokay Large, bright red, seeds. August–November Queen Large, bright to dark red, seeds. June–August
Almeria Large, golden. August–October Calmeria Longish, light green. October–February Perlette Green, seedless, compact clusters. May–July Thompson Seedless, green to light gold. June–November
Source: The Fresh Approach to Grapes (United Fruit & Vegetable Associat ion, n.d.).
Storing This Food
Wrap grapes in a plastic bag and store them in the refrigerator. Do not wash grapes until you are ready to use them.
Preparing This Food
To serve fresh grapes, rinse them under running water to remove debris, then drain the grapes and pick off stems and leaves.
To peel grapes (for salads), choose Catawba, Concord, Delaware, Niagara, or Scup- pernong, the American varieties known as “slipskin” because the skin comes off easily. The European varieties (emperor, flame, Tokay, Muscat, Thompson) are more of a challenge. To peel them, put the grapes into a colander and submerge it in boiling water for a few seconds, then rinse or plunge them into cold water. The hot water makes cells in the grape’s flesh swell, stretching the skin; the cold bath makes the cells shrink back from the skin which should now come off easily.
What Happens When You Cook This Food
How Other Kinds of Processing Affect This Food
Juice. Red grapes are colored with anthocyanin pigments that turn deeper red in acids and blue, purple, or yellowish in basic (alkaline) solutions. As a result, red grape juice will turn brighter red if you mix it with lemon or orange juice. Since metals (which are basic) would also change the color of the juice, the inside of grape juice cans is coated with plastic or enamel to keep the juice from touching the metal. Since 2000, following several deaths attributed to unpasteurized apple juice contaminated with E. coli O157:H7, the FDA has required that all juices sold in the United States be pasteurized to inactivate harmful organ- isms such as bacteria and mold.
Wine-making. Grapes are an ideal fruit for wine-making. They have enough sugar to pro- duce a product that is 10 percent alcohol and are acidic enough to keep unwanted micro- organisms from growing during fermentation. Some wines retain some of the nutrients originally present in the grapes from which they are made. (See wine.)
Drying. See r aisins.
Medical Uses and/or Benefits
Lower risk of cardiovascular disease, diabetes, and some forms of cancer. Grape skin, pulp, and seed contain resveratrol, one of a group of plant chemicals credited with lowering cholesterol and thus reducing the risk of heart attack by preventing molecular fragments called free radicals from linking together to form compounds that damage body cells, leading to blocked arteries (heart disease), glucose-damaged blood vessels (diabetes), and unregulated cell growth (cancer).
The juice from purple grapes has more resveratrol than the juice from red grapes, which has more resveratrol than the juice from white grapes. More specifically, in 1998, a team of food scientists from the USDA Agricultural Research Service identified a native American grape, the muscadine, commonly used to make grape juice in the United States, as an unusually potent source of resveratrol.